JPH0348091B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a screw conveyor, and in particular to a device that takes into consideration application to a decanter centrifugal separator. the row of wear-resistant members is mounted on the working surface of the screw conveyor along its contour with a longitudinal edge surface and widened in accordance with the helical contour of the screw conveyor. the wear-resistant members are lined up and protrude from the outer shell, and the end surfaces of the wear-resistant members abut and extend generally radially; the wear-resistant members are supported on the screw conveyor by a support device for the wear-resistant members; The wear-resistant member support device is held on the screw conveyor between successive wear-resistant members.

The wear-resistant member prevents wear of the helical portion of the screw conveyor when the transported object damages the surrounding area, and is generally made of a carbide compound such as tungsten carbide or a carbide compound such as aluminum oxide. It is made of a pottery material, in other words, a material having a coefficient of thermal expansion different from that of the material of the helical portion of the screw conveyor, which is usually steel. For this reason, it has proven inappropriate to attach the wear-resistant element directly to the helix of the screw conveyor by brazing or gluing; A method suitable for mechanically attaching to the surface of a component has been sought.

A certain prior art discloses a screw conveyor paying attention to the above, and this device includes a lower side of each wear-resistant member, that is, a side of the wear-resistant member facing the helical surface of the screw conveyor; A complementary dovetail shape is provided on the wear-resistant member support block which is welded to the helical surface. In plan view, this dovetail converges on the wear-resistant member outwardly from the axis of the helix of the screw conveyor, while on the support block it diverges outwardly. The wear-resistant member is inserted into a wedge-shaped space identified between successive support blocks, starting from the inner end of the space and then outwardly until it is held aligned between opposing dovetails. driven by The wedge serves to create specific tensile and bending stresses in the strip of wear-resistant member adjacent to the dovetail. If the screw conveyor rotates at high speed during operation, for example in a centrifugal separator, the wear-resistant element is subjected to centrifugal forces that increase the wedge action, so that the wear-resistant element The stress increases further. However, the above-mentioned materials that are commonly used to make wear-resistant components are relatively hard and therefore cannot support the large tensile and/or bending stresses that are applied.

It is an object of the present invention to provide a new device for mounting wear-resistant components in such a way that unnecessary tensile and/or bending stresses are avoided in the wear-resistant components. .

According to the present invention, the support device for the wear-resistant member is provided with an axially symmetrical guide surface, the diameter of which is made smaller as it approaches the helical portion of the screw conveyor;
The axis of symmetry of the guide surface and the helical portion of the screw conveyor intersect at one point on the radial dividing line between the wear-resistant members, and the guide surface of the half of the support device for the wear-resistant member It is possible to provide a screw conveyor characterized in that each end face of the wear-resistant member is provided with a recess defining a guide surface that compensates for this.

In the screw conveyor according to the present invention, the position of the wear-resistant member relative to the surface of the helical portion is determined regardless of whether each wear-resistant member is parallel to the helical portion of the screw conveyor or on the circumference of this helical portion. is specified only by the geometric shape of the support device for the wear-resistant member and the recess in the end face of the wear-resistant member that supplements this. In reality, the support device for the wear-resistant member and the recess in the end face of the wear-resistant member are made with such tolerances that after assembly there is a narrow gap between their opposing guide surfaces, and this gap is are filled with a suitable filler, for example an epoxy resin, which hardens to adhesively bond the components and at the same time absorb the forces that occur during operation between each wear-resistant member and its support device. The elasticity that can be sufficiently transmitted to an appropriately sized area of the guide surface is formed. The advantages of this are, firstly, that no stress is created in the material of the wear-resistant element due to its mounting on the helix of the screw conveyor, and secondly, during operation. The point is that the pressure generated in the band at the edge of the wear-resistant member by the forces generated, in particular by the centrifugal force, is only a compressive stress. It is well known that carbonized compounds, oxides, and other wear-resistant materials generally have extremely high compressive strengths.

According to a feature of the invention, the support device for the wear-resistant parts can be riveted to the helical part of the screw conveyor and has a conical head, which conical head is attached to each of the wear-resistant parts associated with this conical head. In complementary correspondence with the conical recess on the end surface, the diameter increases toward the outside.

In an alternative embodiment, the support device for the wear-resistant element has a stud, which bolt is welded to the helix of the screw conveyor, and the nut associated therewith has a conical guide surface, which guide The surface is complementary to the conical guide surface of the recess in the end face of the wear-resistant member.

A portion of the wear-resistant member parallel to the outer edge of the helical portion of the screw conveyor may have a stepped cross-sectional shape, and the step is a portion far from the helical portion in the portion parallel to the outer edge of the helical portion. of,
It is provided in such a way that it is retracted from one end surface of the portion closest to the spiral portion, and correspondingly protrudes from the other end surface of the portion closest to the spiral portion. Next, the head or nut of the support device for the wear-resistant member is covered with a portion of the wear-resistant member outside the step to prevent the head or nut from being worn by abrasive objects to be transported. Protect.

The above embodiment can be realized using a device made of wear-resistant members, and the members constituting this device are combined with a backing member made of a malleable material, and the support of the wear-resistant members is It is held in the helical portion of the screw conveyor by a device combining two parts and a tile made of a wear-resistant material, which tile is held on the front side of the mounting member and by the above-mentioned wear-resistant member. The screw conveyor is formed into a shape that differs from the backing member in the direction of the outer periphery of the screw conveyor by a method similar to that used to create a step. Furthermore, regarding the wear-resistant material itself, since the support device is aligned only with the backing member, even if the wear-resistant member and its combined support device come into contact, the contact will not occur. As a result, no internal stress is generated in the wear-resistant member itself.

Further, each end face of each backing member disposed on the outside and inside of the recess for receiving a heat resistant member includes an obtuse angle close to 180°, and the end face of the wear resistant tile has a radius are substantially equal in shape, like a rounded arc, converge at the end of the tile that protrudes beyond the backing member, and separate at the other end of the tile. This embodiment is particularly suitable for use as a screw conveyor in a decanter centrifuge, the helical part of which has a combination of circular and conical cross sections; The solids settled in the decanter are moved toward an outlet at the end of the helical portion having a conical cross section. If the shape of the wear-resistant member itself is as described above, the working surface of the entire conical portion of the screw conveyor can be covered with the same wear-resistant member, as is clear from the above-mentioned prior art. No unnecessary gaps are created between the tiles of the wear-resistant member. It is clear that the above-mentioned gaps are created between the backing members, but in the arrangement as described above, the gaps between the backing members are wear-resistant so that the side facing the transported object is connected without any gap. Since it is covered with the member, the gap between the backing members is rendered harmless.

Hereinafter, embodiments of the present invention will be explained in detail with reference to slightly schematic drawings.

The centrifugal separator shown in FIG. 1 has a drum 1 and an inner rotor 2 coaxial with the drum 1, both drum 1 and rotor 2 having a conical shape over their entire longitudinal length. The ends of the drum 1 are supported by two bearings 3 and 4. The short protruding shafts 5, 6 shown on the left side of FIG. 1 are connected to a drive (not shown) which rotates the drum and rotor in the same direction at slightly different speeds.

A double screw conveyor is held in the rotor 2, and this screw conveyor has a spiral portion 7,
It has 8. The difference between the rotation speed of the drum and the rotation speed of the rotor mentioned above corresponds to the relative rotation when the rotor 2 rotates in the direction shown by the arrow 9, so that the helical parts 7 and 8 The solid matter settled in the separation space 10 of the separation device is moved to the right side of the figure.

The raw material to be separated into solid and liquid phases is fed through a fixed tube 11 and is spread through a short hollow bearing 12 of the drum 1 into said hollow rotor 2 . The flow of this raw material is from the inside of the rotor to the hole 1 in the wall of the rotor.
3 to reach the separation space 10. The settled solids are discharged out of the drum 1 through the hole 14 on the right in FIG. leaks to. This hole 15 defines the height 16 of the liquid level inside the drum.

On the active surface 17 of the spiral portions 7, 8 of the screw conveyor, that is to say the surface which serves to convey the settled solids towards the holes 14, wear-resistant elements are provided, essentially in continuous rows. They are held on the outer shell 18 of the working surface 17 so as to be lined up. Please refer to FIGS. 2 and 3 for this. In this embodiment, each wear-resistant member is made of a sintered tile 19, for example a carbonized compound or ceramic material. In plan view, each tile 19 has a trapezoid-like shape having a linear outer edge 20 slightly protruding from the outer contour of the spiral portion of the screw conveyor and two end surfaces 21 converging on the inside. The tiles are installed so that they are in contact with the end surfaces of adjacent tiles and there is no gap between them.

The tiles 19 are attached to the screw conveyor by means of a support device 22 of wear-resistant material shown in FIG.
3 and a conical head whose diameter increases outwardly. The apex angle of the side surface or outer edge surface of this conical head is approximately
Can be set to 30°. Each support device 22 serves to connect and mount two tiles 19a, 19b (FIG. 4), and this support device is mounted between the tiles on the drive surface of the helical portion of the screw conveyor. In this case, the end face 21 of each tile has a recess 25, each of which is complementary to one half of the conical rivet head 24.

Tile 19 including the recess 25 and support device 22
is dimensioned to form a narrow gap between the rivet head 24 and the adjacent recess 25. Although this gap is shown exaggerated in FIG. 4 for clarity, it can actually be approximately 0.1 mm or slightly larger. This void is filled during assembly with an epoxy resin or similar material as described above, which resin, after curing, forms a bond between the rivet head and the tile, so that each of the geometrically defined tiles The position is corrected by the two coupled support devices 22. If the surface of the tiles 19 arranged toward the screw conveyor is flat, a narrow gap is also created there, which gap is filled with the filling adhesive material.

FIG. 5 shows 2 connected to the screw conveyor.
An alternative mounting method for the mounting of tiles 19a, 19b is shown, in this case a short screw 26 welded to the helix 7 of the screw conveyor and a nut 27 screwed onto this short screw, which It has a conical shape toward the outside and corresponds to the rivet head 24 shown in FIG.

Although the tiles 19 are shown in direct contact along their end faces 21, there may also be a narrow gap which is filled during assembly with the filling adhesive described above.

6 to 9 show an improved embodiment of the wear-resistant member, in which case the wear-resistant member includes a backing member 28 made of stainless steel or a malleable material; The tile 29 is made of a flexible material and held by the backing member 28.

The backing member 28, like the wear-resistant member 19 described above, has a roughly trapezoidal shape with a conical recess 30, and has the recess 30 on its end surface, and this recess 30 A complementary conical support member (not shown) is received by means of wear-resistant members 28, 29 mounted on the screw conveyor (not shown). The two portions 31a, 31b of each end face are respectively disposed on the outside and inside of each of the recesses 30 to form an obtuse angle radially, and in this embodiment, the obtuse angle is approximately 175°C, and the apex thereof is Recess 30
coincides with the center of The wear resistant tile 29 is held on a surface 29 of a backing member 28, which is oriented away from the screw conveyor by two pins 33, which are oriented away from the screw conveyor. It is pushed into the backing member and received in two holes in the tile 29 so that the gap is narrowed. When the wear-resistant members 28, 29 are joined, the gap is filled with a suitable filler adhesive, which filler adhesive is applied to the surface of the tile 29 and the opposing surface.

End face 3 of the rightmost tile 29 in Figures 6 and 7
4 has a convex arcuate shape, and this arcuate shape forms part of a circle, the center of which coincides with the center of the concave portion 30 immediately below, and the left end surface 35 of this tile has a concave arcuate shape, This arc is a part of a circle, this circle has the same radius as the above circle, and the center of this circle is at the recess 3.
It coincides with the center of the circle containing 0. By making the shape of the tiles as described above, the wear-resistant members 28 and 29 having the same shape can be used to form a row of wear-resistant members along the outer circumference of the screw conveyor whose diameter varies over a wide range. can be installed side by side without any gaps. This is illustrated in the drawings from FIGS. 9a to 9c, which illustrate the alignment of the screw conveyor with two articulated wear-resistant members 28, 29. The mutual arrangement of parts with different diameters is shown.

Figure 9a corresponds to the upper limit of the range of variation of the diameter, in which the two backing members are adjacent to each other along the outer part 31a of their end faces, while the inner face part A wedge-shaped gap is formed between 31b. FIG. 9c shows the position of the wear-resistant member when the diameter is the smallest, in which the end faces 31b are in contact with each other, and FIG. 9b shows the position of the wear-resistant member when the diameter is at an intermediate value. Correspondingly, at this position, a gap is created between the outer part of the backing member and the inner part of the recess. However, in all of the shapes described above, the arcuate end surfaces 34, 35 of the wear-resistant tile 29 are in an abutting relationship, so that their working surfaces provide a practically continuous wear resistance of the helical portion of the screw conveyor. This wear-resistant surface is aligned in the direction in which the transported object is transported.

In this example, the support member and the wear-resistant member are shown as having conical guide surfaces;
The desired effect can also be achieved with a rotating surface of a different shape. For example, the rivet head shown in Fig. 4 is a rivet head consisting of an outermost cylindrical part (when viewed from the surface of the spiral part of the screw conveyor) and an innermost cylindrical part, and the diameter of the innermost cylindrical part is the outermost part. It can be replaced with something smaller than the cylindrical part. The nut shown in FIG. 5 can also be modified to correspond to this. Additionally, the present invention is applicable to any helical screw conveyor that includes a rotating helix within a fixed tube or groove for conveying abrasive materials.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a decanter centrifugal separator having a screw conveyor according to the present invention, with the outer reservoir of the spiral portion omitted for clarity, and FIG. 2 shows the screw conveyor described above. FIG. 3 is an enlarged partial sectional view taken along the line - of Fig. 2, and Fig. 4 is an enlarged view taken along the line - of Fig. 2. FIG. 5 is a corresponding partial sectional view showing an improved embodiment of the support device for the wear-resistant member, and FIG. 6 is a corresponding partial cross-sectional view of the wear-resistant member attached to the screw conveyor. an elevational view of an alternative embodiment; FIG. 7 is a sectional view taken along the line - of FIG. 6;
FIG. 8 is a drawing showing the end portion of the wear-resistant member seen from the direction of the viewing arrow in FIG. 6, and FIGS. 9a, 9b, and 9c correspond to the drawings from FIGS. Figure 3 is a scaled-down view of three views showing how the based wear-resistant member can adapt to changes in the diameter of the screw conveyor; 1...Drum, 2...Inner rotor, 3, 4...
... Bearing, 7, 8 ... Helical part, 9 ... Rotation direction of the helical part, 10 ... Separation space by centrifugation, 11 ... Inlet of material to be centrifuged,
13... Inlet to the separation space for the material to be centrifuged, 14... Outlet for separated solid matter, 15...
...Discharge port for separated liquid, 17... Working surface of the spiral portion, 19, 19a, 19b, 19c...
Wear-resistant member, 22... support device for wear-resistant member, 28... backing member.

Claims (1)

[Scope of Claims] 1. Approximately trapezoidal wear-resistant members are provided on the working surface of the screw conveyor in a continuous row along the outer circumference of the screw conveyor, The outer surfaces of these wear-resistant members extend radially outwardly beyond the contour of the helix of the screw conveyor, and the wear-resistant members are attached to the helix of the screw conveyor between the wear-resistant members. In a screw conveyor supported by a fixed support device on the spiral portion of the screw conveyor, the support device is provided with a guide surface having a small diameter in the direction of the surface of the screw conveyor spiral portion and axially symmetrical, and the above-mentioned The axis of symmetry of the guide surface intersects the point of the radial dividing line between the corresponding wear-resistant members and corresponds to the half of the guide surface provided on the support device at the end face of said wear-resistant member. A screw conveyor characterized by having a recessed portion forming a guide surface. 2. The screw conveyor according to claim 1, wherein the guide surface of the support device is formed by a conical head, and the support device is fixed to the helical portion of the screw conveyor by rivets. 3. The support device has a threaded bolt welded to the helical portion of the screw conveyor and a nut with a conical guide surface, and a recess corresponding to the conical guide surface of the nut is formed on the end surface of the wear-resistant member. The screw conveyor according to claim 1, characterized in that the screw conveyor is formed. 4. The screw conveyor according to claim 2 or 3, wherein the wear-resistant members are partially overlapped to form a stepped portion.